CA2142608C - Biodegradable two-cycle engine oil compositions and ester base stocks - Google Patents

Abstract

Lubricant compositions comprising biodegradable ester base stocks are provided for water-cooled or air-cooled two-cycle engines.

Description

. v wo 9aios~as ~criu~~3~o~s7o i BIODEGRADABLE TWO-CYCLE ENGINE OIL
COMPOSITIONS AND ESTER BASE BTOCRB
g3ACKGROUND OF THE IN~ENTION

1. Field of the Invention The present invention relates to two-cycle engine oiI

compositions and to ester base stocks which are components thereof. The, compositions of the invention require no miscibility-enhancing salvents and are readily biodegradable:

2. Description of the Related Art The two-cycle (two stroke) engine has gained considerable papularity as a power source for such devices 1O as outboard motors, snow mobiles, mopeds and a variety of landscaping equipment, e.g., lawnmowers, chain saws, string trimmers and blowers. The widespread use of two-cycle engines is due primarily to their simple design and lightweight construction, their ability to provide high power output with quick starts at low temperature and their re2atively low cost:

Two-cycle engines are :operated using a mixture of gasoline and a lubricant in prescribed proportions. The lubricant must provide satisfactory performance characteristics under severe operating conditions.

Lubricants for two-cycle engines are generally composed of a, mineral oil or synthetic base fluid, performance additives) and a solvent, ordinarily a relatively low boiling petroleum distillate, to enhance gasoline/lubricant miscibility.

The technologies developed to date for reducing exhaust emissions from four-cycle car and truck engines have not been successfully adapted to two-cycle engines.

Hence, there is growing public concern over the high levels . . : 2'lv:~ 2 6 0 8 of hydrocarbon emissions from these small engines, as hydrocarbons do not readily biodegrade.
The hydrocarbon emissions are a consequence of the basin design of the engine. Specifically, in the power stroke of a typical two-cycle engine, air, oil and fuel are drawn into the crank case as the combined charge is compressed in the space above the piston. In the exhaust stroke, the burnt gases are discharged through exhaust ports, and a fresh combustible charge is transferred from the crank case to the space above the piston. Because the exhaust ports open before and close after transfer of the fresh combustible charge occurs, as much as 20% of the Fresh. charge will be.discharged unburnt with-the exhaust.
Consequently, hydrocarbon emissions far'exceed the level of emissions from a comparable four-cycle engine.
Water-cooled outboard motors exhaust directly into the water, giving rise to water pollution, whereas the other devices mentioned above, which are equipped with air-cool~d two-cycle engines; produce emissions that pose a serious air pollution problem. For example, the California Air Research Hoard has determined that many two-cycle engines produce up to fifty times the pollution of truck engines per horsepower hour.
The above-noted pollution problems are exacerbated by the presence of volatile organic solvents in the lubricant. Moreover; some of the solvents used as miscibility enhancers, such as Stoddard solvent, have relatively low flash points, thus creating a potential fire risk, which is of particularwconcern in connection with the storage and transportation of such products.
Thus, a need exists for a two-cycle engine oil composition which is formulated so as to prevent pollution 'by protecting against emission of harmful hydrocarbons into the environment, and to reduce the hazard potential of the solvent-containing lubricants, especially in storage and in transit. These objectives must be obtained, however, while simultaneously satisfying stringent performance standards, SUBSTITUTE SKEET

vV0 94/05745 PCT/US93/07570 e,.g., good lubricity and detergency, particularly on piston _ rings, superior anti-seizure properties and high gel/f 1oc resistance, and providing optimum miscibility of lubricant and fuel over the applicable range of operating conditions.
SOMMARY OF THE TNVENTION
In accordance with the present invention, there is provided a biodegradable ester base stock and a two-cycle engine oil composition containing same which is adapted for use in both water-cooled and air-cooled two-l0 cycle engines. The oil composition of the invention is formulated so as to eliminate the need for a conventional solvent, thereby substantially reducing not only the pollution potential of two-cycle engines lubricated therewith, but the hazard risk inherent in solvent containing formulations.
According to one embodiment of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, which consists essentially of a blend of (a) a first polyol ester comprising, as its reactive components, a neopentylpolyol and a C~6-C20 branched chain, saturated monocarboxylic acid, and (b) a second polyol ester comprising, as its reactive components, a neopentyl~polyol and a carboxylic acid selected from the group consisting of at least one CS-Clo linear, saturated monocarboxylic acid, or at least one C16-C2o linear or branched chain, unsaturated monocarboxylic acid.
According to another embodiment of this invention, there is prodded an ester base stock for a two-cycle engine oil composition, which consists essentially of a blend of (a) ai first polyol ester comprising, as its reactive components, a neopentyl polyol and a C8-Clo linear, saturated monocarboxylic acid and (b) a second complex polyol ester comprising, as its reactive components, a neopentyl polyol; a Cs-C12 dicarboxylic acid and a CS-Clo linear or branched chain, saturated monocarboxylic acid.
A solvent substitute, if desired, may optionally be incorporated in the ester base stocks of the invention.
suss-rnu-r~ s H ~~T

Suitable for this purpose are any of various relatively low molecular weight esters comprising as the reactive components thereof, a C8-C13 linear or branched chain monohydric alcohol and a C5-C12 linear or branched chain carboxylic acid.
The ester base stocks of the invention are characterized by their superior biodegradability, flash point and viscosity properties, as compared with two-cycle engine lubricant base stocks heretofore available. The biodegradability of the ester base stocks of the invention is greater than 80%, as determined by CEC-L-33-T-82. Each of the ester base stocks of the invention has a flash point of at least 175°C. The kinematic viscosity of the ester base stocks of the invention is less than 15 cSt at 100°C.
The two-cycle engine oil compositions of the invention are composed of the above-described base stocks and any of the performance additive packages known in the art, preferably ashless detergent/dispersant additives, e.g., reaction products of polyamines and relatively long chain fatty acids. In addition to having the desirable biodegradability, flash point and viscosity properties noted above, the two-cycle engine oil compositions of the invention have excellent miscibility with gasoline, in fuel/oil ratios between 16:1 to 100:1.

I

4a According to one aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, said base stock consisting essentially of a blend of (a) a first polyol ester comprising, as its reactive components, a neopentylpolyol and a C16-Czo branched chain, saturated monocarboxylic acid and (b) a second polyol ester comprising, as its reactive components, a neopentylpolyol and a carboxylic acid selected from the group consisting of at least one CS-Clo straight chain, saturated monocarboxylic acid, or at least one C16-C2o straight or branched chain, unsaturated monocarboxylic acid;
and, optionally, a relatively low molecular weight ester comprising, as its reactive components, a C$-C13 straight or branched chain monohydric alcohol and a CS-Clz straight or branched chain carboxylic acid, said ester base stock having the following characteristics: (i) biodegradability of >_ 80%, as determined by CEC-L-33-T-82; (ii) flash point of >_ 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C.
According to another aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, consisting essentially of from about 20% to about 60% of trimethylolpropane triisostearate and from about 40% to about 80% of trimethylolpropane tripelargonate, based on the weight of said ester base stock.
According to still another aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, consisting essentially of from about 15% to about 55% of trimethylolpropane triisostearate and from about 45% to about 85% of an ester comprising, as its reactive components, trimethylolpropane and a mixture of I

4b caprylic acid and capric acid, based on the weight of said ester base stock.
According to yet another aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, consisting essentially of from about 35% to about 90% of trimethylolpropane triisostearate and from about 10% to about 65% of trimethylolpropane trioleate, based on the weight of said ester base stock.
According to a further aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, consisting essentially of from about 35% to about 70% of trimethylolpropane triisostearate and from about 30% to about 65% of a mixture of CS-C9 saturated monocarboxylic acids, based on the weight of said ester base stock.
According to yet a further aspect of the present invention, there is provided a biodegradable two-cycle engine oil composition comprising: (A) an ester base stock consisting essentially of a blend of (a) a first polyol ester comprising, as its reactive components, a neopentylpolyol and a C16-Czo branched chain saturated monocarboxylic acid and (b) a second polyol ester comprising, as its reactive components, a neopentylpolyol and a carboxylic acid selected from the group consisting of at least one CS-Clo straight chain, saturated monocarboxylic acid or at least one C16-Czo straight or branched chain, unsaturated monocarboxylic acids; and, optionally, a relatively low molecular weight ester comprising, as its reactive components, a C$-Cz3 straight or branched chain monohydric alcohol and a CS-Clz straight or branched chain carboxylic acid, said ester base stock having the following characteristics: (i) biodegradability of >_ 80%, as 4c determined by CEC-L-33-T-82; (ii) flash point of >_ 175°C;
and (iii) kinematic viscosity of less than 15 cSt at 100°C;
and (B) a detergent/dispersant additive, said composition having the following characteristics: (i) biodegradability of >_ 80%, as determined by CEC-L-33-T-82; (ii) flash point of >_ 175°C; (iii) kinematic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/oil ratio of 16:1 to 100:1, of <_ 110% of reference oil, as determined by ASTM-4682, using Citgo-93738 as said reference oil for category 3, according to SAE J1536.
According to still a further aspect of the present invention, there is provided an ester base stock for a two-cycle engine oil composition, said base stock consisting essentially of a blend of (a) a first polyol ester comprising, as its reactive components, a neopentylpolyol and a C8-Clo straight chain, saturated monocarboxylic acid and (b) a second complex polyol ester comprising, as its reactive components, a neopentylpolyol, a C6-C12 dicarboxylic acid and a CS-Clo straight or branched chain, saturated monocarboxylic acid; and, optionally, a relatively low molecular weight ester comprising, as its reactive components, a CB-C13 straight or branched chain monohydric alcohol and a CS-C12 straight or branched chain carboxylic acid, said ester base stock having the following characteristics: (i) biodegradability of >_ 80%, as determined by CEC-L-33-T-82; (ii) flash point of >_ 175°C;
and (iii) kinematic viscosity of less than 15 cSt at 100°C.
According to another aspect of the present invention, there is provided a biodegradable two-cycle engine oil composition comprising: (A) an ester base stock consisting essentially of a blend of (a) a first polyol ester, comprising, as its reactive components, a 4d neopentylpolyo~_ and a C'E,-C1o strai.gh.t cha=in, saturated monocarboxylic acid anc; (b) a second complex polyol ester comprising, as its react;:ive components, a neopentylpolyo:l, a C6-C12 dicarbox:~rlic acicand a CS-C:lc~ straight or branched chain, saturated monocarhoxylic acid; anti, optionally, a relatively low molecular weight ester Lomprising, as its reactive components, a C,3--C13 straight, or branched chain monohydric alcohol and a CS-c~lz strG.ig:ht or_ branched chain carboxylic acid, said e:~ster base stock having the following characteristic:: (i) k:~iodegrada.bil.ity of >_ 80%, as determined by CEC-L-33--T--82; (ii) flash point of >_ 175°C;
and (iii) kinematic vi:,cosity of less than 15 cSt at 100°C;
and (B) a dete:rgent/di~~persant addi_t;ive, said composition having the fo=Llowing crr.aracterist:.ic:s: (i) biodegradability of >_ 80%, as d~~terminecl by CEC--L-33-T-82; (ii) flash point of >_ 1'75°C; (i.ii) kineruatic viscosity of .Less than 15 cSt at 100°C; and (iv) miscibi.l.ity with gasoline, in a f=uel/oil ratio of 16:1 to 100:1, of. <_ 1100 of reference oil, as determined by ASTM-468:;, using C'it<~o-93738 as said reference oil for category 3, ac~:~.ox~ding to SAE J1536.
In further a:~pects, the invention provides: A
biodegradable two-cycle engine oii composition comprising:
(A) about 85% of an est:e~r base sto;~k consisting essentially of a blend of trirnethy:_c>lpropane trii.sostearate and trimethylolpropane trip~E>largonate i.n a weight ratio of about 0 . 7 : 1 . 0 , said ester ba,:~E~ stock having t;he fol:Lowing characteristics: (i) b:iodegradability of_ >_ 80'%, as determined by CEC-L-33-'~,--82; (ii) flash point of >_ 175°C; and (iii) kinemati.c viscos.i.t:y of less t=han j 5 c~~t at 100°C; and (B) about 15% of an additive selected from the group consisting of a polyarricie, a alkenylsuc~c_°. ininuide, a boric.
acid-modified alkenylsuc.~.~~inimide, a pheriolir. amine, a 4e succinate derivative .::end a combination of said additives, said percentages bein~:~ i>ased on the weight of said composition, said com_:>osi.tion hav~~ng the fol-owmg characteristics: (i) >:~iadegradability of >_ BCio, as determined by CEC-L-3.3--~I'-82; {ii) flash point. of >_ 175°C;
(iii) kinemat:ic visco~4:~it.y cf less than: 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/o:il. ratio of 16:1 to 100:1, of <_ 11_Oo o.reference oil, as determined by ASTM-4682, using Citgo-937:?~8 as said reference o:il. for category 1~~ 3, according to SAE J:'~.5i6.
A biodegradable two-r_ycle engine oil composition comprising: {.A) about 850 of an e;~ter base stock consisting essentially of a blend c.~f trimethlrlolpropane triisostearate and an ester ~omprisin:,g, as its reactive components, trimethylolpzv~pane anc. a mixture of caprylic acid and capric acid, in a wF~~ight rat_;.o of about ~...2 to 1.0, said ester base stock having the foll<.:wi.ng characteristics: (i) biodegradability of >_ 800, as determined by C'EC-L-33-T-82;
(ii) flash point of >_ 175°C; and (ii.i) kinematic viscosity of less than 15 ~~St at 1()0°C; and {B) about 15 ~ of an addit=ive selected from thE: groi:rp consisting of a polyamide, a alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic am_ne, a succinate derivative and a combina~ion of raid additives, said percentages being based on the weight of: said composition, said composition having the following oharacterists_cs: (i) biodegradability of >_ 80%, as c3eterminE:d by CEC-L-33--T-82; (_ii) flash point of >_ 175°C; (iii) kinem~~t=is viscosity of lees than 15 cSt at 100°C; and (iv) miscibi_:L:ity with gasoline, in a fuel/oi~~_ ratio of 16:1 to 100:1., of < 110'0 of reference oil, as determined by ASTM-46Fs2, using Cit:go-93'738 as said reference oil for category 3, acvcord_ing to :>AE J1536.

4f A b:iodegradaOl.e two-cycle engine oil composition comprising: (A.) about e~~-, of an ester base stock consisting essentially of a blend of t.rimethylol.propane t;riisostearate and trimethylclpropane t.rioleate i:n a weight ratio of a~>out 3.0:1.0, said ester ba_~e~ stock having the :following characteristics: (i) b~_c>degradability c>f >_ 80'%, as determined by CEC-L-33--~'-82; (ii; Clash point of 175°C; and (iii) kinemat:ic viscos~_t.y of Less than 15 cSt at 100°C; and (B) about 15% of an ad~::~i.tive selected from the group consisting of a polyam:~_cle, a alkenylsuccinimide, a boric' acid-modified alkenylsa.zcc:i-nimide, a prnenol.ic amine, a succinate der:ivati.ve arid a comb:Lnation c;f said additive~~, said percentages being Erased on the weight of sad composition, said comp::~~~ition having the following characteristics: (i) b:~odegradability of _>_ 80~, as determined by CEC-L-33 -T--82; (ii ) flash point of >_ 175°C;
(iii) kinemat:ic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with _~asoline, in a fuE=1/oil ratio of 1.6:1 to 100:1, of ._ 110% of reference oil, a~ determined by F,STM-4682, using C.itgo-9373.3 as said reference oil for category 3 , according to SAE Jl ~:>:~; Ei .
A method of lubricating a two-cycle engine which comprises brin.gin~.~ the components of- said engine which are to be lubricated :into ~:~c>ntact: w.it~h are ef fecti,,re amount: c>f a composition comprising about 850 of an ester base stock consisting essentially of= a blend ;~f trimethy:Lolpropane triisostearate: and trirnet~hylc>lpropane t: z: ipela:rgonate, in a weight ratio of about c~.'7:1.0, and about. 15% of an ashless additive selected from t:he group con.sr_sting of a polyami.de, an alkenylsuccinimide, ~~ boric acid--modified alkenylsuccini.mide, a E?~ienolic amine, a succinate 4g derivative, ar.d a combinat:i.on of said additives, said percentages being base~:x on the weight of said composition.
DES(~RIPTION O:f THE PREFERRED EMBODIMENTS
A. Ester Ba~:~Ee Stocks Preferred tw::~-cycle engine oil base stocks of the invention are blends c~msisting essentially o:E a first polyol ester formed by t:he reaction of_ a neopentyl polyol and a C16-Czo branched chain, saturated monocawboxylic acid and a second ~~olyol esl:Far formed. by the reaction of a neopentyl polyol and a carboxylic acid selected from the group consisting of (i j at: least one C;-C1o straight chain, saturated monocarboxyl:i.c acid or (ii) at least one C16-C;;o straight or branched c:';za:in, unsaturated monocarboxylic acid.

~y ~"vV0 94/05745 , ",1'4'2 6 4 ~ PCT/US93/07570 a Suitable neopentyl polyols for preparation of the ester blends described above include trimethylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, neopentylglycol and~mixtures of any two 5 or more of such neopentyl polyols. Trimethylolpropane is particularly preferred as the neopentyl polyol reactant in both components of the preferred ester blend described immediately above.
Thepreferred acids which may be used to form the first polyol ester include the C16-Cia' "isoacids", isostearic acid being particularly preferred: Isostearic acid is a readily available commercial product obtained as a' by-product from the manufacture of polymer fatty acids by the polymerization of naturally-occurring, unsaturated Cls fatty acids. It is obtainable under the trademark Emersol~
871 and Emersol~ 875 from Henkel Corporation,, Emery Group, Cincinnati, Ohio. By way of illustration of the preparation of'polymeric fatty acids, reference may be had to U.S: Patents Nos. 2,793,219 and 2,955,121. Polymeric fatty acids from the polymerization of unsaturated fatty acids are primarily composed of dimes and trimer acids;
however, there may also be present in the mixture some higher acids and unreacted monomer. A portion of the monomer acid rearranges during:the polymerization to yield a branched-chain Cla monocarboxylic acid product which is then isolated by distillation. Although the exact structure of this ClB branched-chain product'has not been fully elucidated, the'principal.components of the acid are methyl-branched isomers.
' Isostearic acid prepared in the manner just described may, contain up to 35% by weight saturated, and some unsaturated straight-chain C~-C18 fatty acids.
Preferably, these straight chain acids will constitute 25%
or less of the isostearic acid reactant. These straight-chain acids are typically present in the isostearic acid as obtained from the polymerization process, however, additional straight-chain acids may be blended with the SUBSTITUTE SHEET

WO 94/05745 ~ ~ PCT/US93/07570 isostearic acid so long as the aforementioned limit~is not exceeded.
Acid component (i) of the second polyol ester in the preferred ester base stock described immediately above ' is preferably selected from the group of eaproic acid, caprylic acid, pelargonic acid, capric acid and mixtures of ' two or more of such straight chain, saturated monocarboxylic acids. Particularly preferred as acid component (i) of the second polyol ester are pelargonic acid; or a blend of caprylic (Cg) and capric (C1o) acids, the latter being'commercially available under the trademark Emery~ 658 from Henkel Corporation, Emery Group, Cincinnati,. Ohio: Mixtures of relatively low molecular weight fatty acids (e.g., Emery~ 1210) may also be used as acid component (i), if desired.

Acid component (ii) of the second polyol ester described is preferably'; selected from th'e group of palmitoleic acid; oleic acid and mixtures of such unsaturated monocarboxylic acids. Oleic acid is particularly preferred as acid component (ii):

The ester base stock blends of the present invent~,on are prepared using conventional mixing equipment and.techniques: In.general, the amount of the first polyol ester in' the preferred ester base stack described : imatediately above should be From about 10% to about 65%, based on the total' weight of the ester base stock, and the amount of the second polyol ester present in the blend should be from about 35% to'about 90% based on the total weight of the base stock.: .Other- preferred ester base s'ta'cks according'~to this invention are blends consisting essentially of a first polyol ester formed by',the reaction of a neopentyl polyol and a C8-Clo straight chain, saturated monocarboxylic acid and a second, complex polyol ester formed by the reaction of a neopentyl polyol, a C6-C12 dicarboxylic acid and a CS-Clo straight or branched chain saturated monocarboxylic acid.

SUBSTITUTE SHEET

,;,:, ' , ~ ~

y'~ P~/US93/07570 rVO 94/05745 The preferred neopentylpolyols used in forming the ester base stock of these alternative embodiments of the present invention are essentially the same as those previously described hereinabove. In this embodiment also, TMP is the most preferred neopentylpolyol.

The preferred acid component of the first polyolester of these alternative embodiments includes pelargonic acid or a blend of caprylic and capric acids (e:g., Emery~ 658), pelargonic acid (e.g., Emery~ 1202) ;

being particularly preferred.

The complex polyol esters used in preparing the last-mentioned base stocks of the invention are preferably prepared using a blend of Gaprylic and capric acids (e. g., - Emery~ 658) as the monocarboxylic acid and adipic acid as the dicarboxylic acid components of the complex ester, typically in a weight ratio from about 2.5:1:0 to about 3.0:1.0,-cap~ylic acid-cupric acid to adipic acid.

Generally; the amount of the first' polyol ester in the ester base stock of these alternative embodiments hould be from about 25% to 'about 85%, based'on the total weight .of the base stock and. the amount of the second polyol ester .component should be from about 15% to about 75%, based on the total weight of the base stock. a:;:

The above-described ester base stocks may be prepared'from relatively pure reagents or from technical grade reagents, e.g.,, mixed polyols or mixed acids, the reagent mixtures being more economical, because commercially available products may be used, without costly purif ication as a' prerequisite .
I

The above-described esters are prepared utilizing conventional esterification procedures. Typically, the quantity of acid charged to the reaction mixture initially is sufficient to provide an excess of about 1.1-1.2% of equivalents of acid over the equivalents of alcohol reacted therewith: An equivalent of acid is defined for the purporses of this specification as the amount containing 1 gram equivalent weight of carboxyl groups, whereas an SUBSTITUTE SHED .

I
WO 94/05745 214 2 6 0 8 PCT/US9~/07570 equivalent of alcohol is the amount containing 1 gram equivalent weight of hydroxyl groups. If the reaction mixture contains both monovalent and divalent acids, the excess preferably is made up of the monvvalent acid. The esterif ication reaction is carried out at elevated temperature while removing water. The reaction may be carried out by refluxing the reactants in an a~eotropic solvent, such as toluene or xylene, to facilitate removal of water. Esterification. catalysts may be used, but are In not necessary for the reaction. Upon completion of the reaction, excess acid and any solvent may be conveniently separated from the ester product by vacuum stripping or distillation.
The ester product thus produced may be utilized as such, or it may be alkali refined or otherwise treated to reduee the acid number, remove catalyst residue, reduce ash content, or other undesired impurities. If the ester product is subject to alkali refining, the resultant product should be washed with water to remove any unreacted excess alkali and the small amount of soap form from the excess fatty acid neutralized by the alkali before using the ester as a base stock and/or lubricant according to this invention.
The ester base stocks of the present invention may optionally include a relatively low molecular weight ester, if desired, as a solvent substitute to enhance fuel/oiI miscibility. The solvent substitute-ester may be formed from the reaction of a monohydric alcohol selected from octanol, nonanol, decanol, undecanol, dodecanol, tridecanol and branched chain isomers thereof, and a carboxylic acid selected from the group of valeric acid, caproic acid, enanthic acid, caprylic acid, gelargonic ~ i acid, capric acid, undecylic acid, lauric acid and branched chain isomers thereof.
B. Two-CVCle Oil Compositions Various detergent/dispersant additive packages may be combined with the above-described ester base stocks SUBSTITUTE SHEET

in formulating the two-cycle oil compositions of the invention. Ashless or ash-containing additives may be used for this purpose, ashless additives being preferred.
Suitable ashless additives include polyamide, alkenylsuccinimides, boric acid-modified alkenylsuccinimides, phenolic amines and succinate derivatives or combinations of any two or more of such additives.
Polyamide detergent/dispersant additives, such as the commonly used tetraethylenepentamine isostearate, may be prepared by the reaction of fatty acid and polyalkylene polyamines, as described in U.S. Patent 3,169,980. These polyamides may contain measurable amounts of cyclic imidazolines formed by internal condensation of the linear polyamides upon continued heating at elevated temperature.
Another useful class of polyamide additives is prepared from polyalkylene polyamines and C19-C25 Koeh acids, according to the procedure of R. Hartle et al., JAOCS, 57 (5): 156-59 (1980).
Alkenylsuccinimides are formed by a step-wise procedure in which an olefin, such as polybutene (MW 1200) is reacted with malefic anhydride to yield a polybutenyl ' succinic anhydride adduct, which is then reacted with an amine, e.g. , an alkylamine or a poly- amine, to form the desired product.
Phenolic amines are prepared by the well-known Mannich reaction (C. Mannich and W. Krosche, Arch. Pharm., 250: 674 (1912)), involving a polyalkylene-substituted phenol, formaldehyde and a polyalkylene polyamine.
Succinate derivatives are prepared by the reaction of an olefin (e. g., polybutene (MW 1200 700-300)) and malefic anhydride to yield a polybutenyl succinic anhydride adduct, which undergoes further reaction with a polyol, e.g., pentaerythritol, to give the desired product.

WO 94/05745 ~ PCT/US93/07570 Suitable ash-containing detergent/dispersant i additives include alkaline earth metal (e. g., magnesium, calcium, barium), sulfonates, phosphonates or phenates or f combinations of any two or more of such additives.
5 The foregoing detergent/dispersant additives may y be incorporated in the lubricant compositions described ~ ' herein in an amount-from about 5 to about 20%, and more preferably from about 10% to about 16% based on the total weight of the composition.
10 Various other additives may be incorporated in the lubricant compositions of the invention, as desired.
These include smoke-suppression agents, such as - polyisobutylene, extreme pressure additives, such as dialkyldithiophosphoric acid salts or esters, anti-foaming _t agents, such as silicone oil, pour point depressants, such as polymethacrylate, rust or corrosion prevention agents, such as triazole derivatives, propyl gallate or alkali metal phenolates or sulfonates, oxidation inhibitors, such as substituted diarylamines, phenothiazines, hindered phenols, or the like. Certain of these additives may be multifunctional, such as polymethacrylate, which may serve ' as an anti-foaming agent, as well as a pour point depressant.
These other additives may be incorporated in the lubricant composition in an amount from about .O1% to about 15%, and preferably from about .O1% to about 6%, based on the total weight of the lubricant composition. The amount selected within the specified range should be such as not to adversely effect the desirable perfarmance properties of ' 30 the lubricant. The effects produced by such additives can a be readily determined by routine testing.
The biodegradability of the ester base stocks/lubricant compositions of this invention is _> 80%, as determined by Co-ordinating European Coun$el standard test method L-33-T-82 (Biodegradability of Two Stroke Cycle Outboard Engine Oils in water), which provides a procedure to evaluate comparatively the biodegradability SUgSTiTUT~ SHEET

f:N.~.
WO 9 /0~ 5 PCT/US93/07570 of two-cycle outboard engine lubricants against the biadegradability of standard calibration materials. In performing this test procedure, test flasks containing a mineral medium, the test oil and a bacterial inoculum (effluent fram a municipal sewage plant), together with flasks containing poisoned blanks, are incubated for 0 to 21 days: Flasks containing calibration oils are run in parallel. The tests are carried out in triplicate at 25+1°C and in darkness.
' At the end of the incubation period the contents of the flasks are subjected to sonic vibration, acidified and extracted with carbon tetrachloride or 1,1,2-trichlorotrif luoroethane. The extracts are then analyzed by infra-red spectroscopy, measuring the maximum adsorption of the CH3-CH2-bond at 2930 cm~l.
Biodegradability is expressed in % as the difference in residual oil contents between the poisoned flasks and the respective test flasks.
Details of reference and standardization lubricants are to be found in the CEC Handbook of ReEerence/Standardization Oils for Engine/Rig Tests. The biodegradability of the ester base stocks of the invention is preferably >_ 90%, as determined by the same CEC standard test method mentioned above. A biodegradability value below 80% for the ester base stocks, according to the aforementioned CEC standard test method, is not considered to be readily biodegradable.
The ester base stocks/lubricant compositions of the invention have.a flash point of >_ 175°C, and preferably > ;250°C. Such flash point properties are a decided improvement over prior art ester base stocks containing miscibility enhancing solvents, such as Stoddard solvent, which has a flashpoint of about 40°C.
The ester base stacks/lubricant compositions of the invention have desirably low viscosities of less than 15 cSt at 100°C. Preferably, the viscosity at 100°C is in the range of 7-9 cSt. At viscosities much above 15 cSt at SUBSTITUTE SNE'~T

21~:~~6~0~
WO 94/05745 PCT/U~93/07570 100°C, the corresponding viscosity at -25°C is such that the miscibility of the ester base stock/lubricant in gasoline is reduced.
The miscibility of the two-cycle engine oil ' composition of the invention with gasoline, in a fuel/oil ratio of 16:1 to 100:1 is generally < 110% relative to a ' reference oil, as determined by ASTM-4682 using Citgo-93738 as the reference oil for category 3, as outlined in SAE
J1536.
The two-cycle engine oil compositions of the present invention are particularly suited, when mixed with an appropriate fuel, for operating outboard motors, snow mobiles, mopeds, lawnmowers, chain saws, string trimmers and the like.
The following examples describe specif is ester base stocks and lubricant compositions embodying the present invention. The base stocks and compositions exempiif ied below represent the best mode presently contemplated by the inventors for practicing this invention. These examples are provided for illustrative purposes only and are not intended to limit the scope of the invention in any way.

A solvent-free biodegradable ester base stock blend, according to the present invention, was prepared from trimethylolpropane triisostearate (about 9:2 weight percent) and trimethylolpropane tripelargonate (about 58 weight percent). The resultant blend has the SUBSTITUTE SHEET

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.

typical characteristics listed below Table I, which also in identifies the method by whic h the specified j characteristics were determined.

TAHLE I

Properties Characteristics Methods f Viscosity, cSt ASTM D-445 100C 6.9 40G 37.1 Viscosity rndex 148 ASTM D-22?0 Viscosity, SUS ASTM D-2161 210F 49.5 100F 188.9 ty, cp ASTM D-2983 s Vis C

Flaeh Point, C 265 ASTM D-92 Pour Point, C -37 ASTM D-97 Acid Value, mg KOH/gm 0.7 AS.TM D-974 Hydroxyl Value mg KOH/gm 2.5 Emery 116.02 Noack Volatility, % Lose 2.2 CEC-L-40-T-87 2 0 Biodegradability Readily CEC-L-33-T-82 Biodegradable*

Specific Gravity, 60/60F 0.9319 ASTM D-1298 Density. lbs,./gal. @60F 7.76. .

(15.6C) :
2 5 * Greater than 80% according to GEC-L-33-T-82 Standard Test Method '-Ester. base stocks having characteristics generally similar to those reported in Table I may be obtained when about 20 to about 60 weight percent of trimethylolpropane triisostearate is blended with about 30 40 to about 80 weight percent of trimethylolpropane tripelargonate.

' A two-cycle engine oil composition having outstanding overall performance properties was prepared by combining 85 weight percent of the specif is ester 35 base stock blend described herein and 15 weight percent of an ashless detergent/dispersant additive, available from Lubrizol~ Corp. under the name Lubrizol~

Additive System.

SUBSTITUTE SHEET

WO /05745 ~ ~ ~ PCT/US93/0757Q

. .. 14 The typical characteristics of the resultant lubricant composition and the standards by which these characteristics were evaluated are set forth below in Table TI.

'~AEIaE II ' .

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Properties Characteristics Methods Viscosity, cSt ASTM D-445 100C 9.04 40C 55.5 Viscosity Index 143 ASTM D-2270 Flash Point, C 257 ASTM D-92 Pour Point, C -36 ASTM D-97 Noack Volatility, % Loss4.7 CEG-L-40-87T

Acid Value, mg KOH/gm 0.59 ASTM D-974 Hydroxyl Value, mg KOH/mg8.0 ROCS Cd 13-60 Color, 0 12 AoCS Td la-64T

TBN, mg KOH/mg 2.94 ASTM D-2896 % Nitrogen 0.16 ASTM D-3228 Chlorine, ppm 6 ASTM D-1317 2 Biodegradability >_ 80% CEC-L-33-T-82 The specific lubricant composition described herein has been certified TC-W3~' by the National Marine Manufacturers Association (NI~iA) , following successful .z completion of certification testing procedures at the SUBSTITUTE SHEET

a .:.v.. ~ 1.
W~ 94J05745 .. ~ 1~ ~ PCTlUS9~/07570 Southwest Research Institute. These test procedures and the results obtain ed are summarized below in Table III. , TABLE III

Results 5 Candidate (Ref.) Test Method A. Bench Tests -,/Evaluation Evaluation Criteria Cloud Point, C -29 ASTM D-2500 Compatability Clear Homogeneous after mixed separately with 10 each reference oil *,**) and stored 48 hours Brookfield (Fluidity)cp ASTM D-2983 @ -25C 5130/Pass Less than 7500 cp 15 Miscibility ASTM D-4682 (Inversions @ -25C) 75(95)/Pass No more than 10% more ' inversions than reference (*) Rust Test, % 3.16(4.04)/Pass NMMA Procedure Equal 2 to or better than reference (*) Filterability, % NMMA Procedure Decrease Change +6.5/Pass +6.5/Pass in flow not greater than 20%

Results , Candidate (Ref.) B. En~,ine Tests /Evaluation Evaluation Criteria 1. OMC Enaine Tests 40 Horsepower Tests 3 (98 Hours) Avg. Piston Varnis h 9.2(8.9)/Paes Not lower than 0.6 below Top Ring Stick 10.0(9.5)/Pass same rating$ of reference .( * ) 70 Horsepower Test 3 5 (100 Hours) Avg. Piston Deposits 6.5(5.0)/Pass Equal to or better than Second Ring Stick 9.6(7.6)/Pass same ratings of reference (***) i SUBSTITUTE SHEET

WO 94/05745 ~ 14 2 6 0 ~ PC:T/US93/07570 2. MercuaZr 15 Horsepower Test (100 Hoursl Scuffing PASS 100 Hours with no stuck PASS rings, plus: a) scuffing within allowable limits (30%) Bearing Stickiness PASS b) Needles must fall easily from wrist pin 1 0 Compression Loss PASS c) 20 psi maximum compression loss (reference (***) run every 5 candidate runs) Overall Evaluation PASS
3. Yamaha lEngrine Tast CE50S Tightening/
' Lubricity Test Torque Drop, lb-in 5.18(5.43)/ Equal to or better than PASS reference ( ** ) within 2 0 90% confidence level CE50S Preignition Test (100 Hours) Major Preignitions 1(1)/PASS Eqval to or better than reference (*) 2 5 * Citgo-93738 (TC-W IT reference oil) ** XPA-3259 *** nR-71591 A solventless, biodegradable ester base stock 30 and lubricant composition, having characteristics similar to those reported in Example 1, above, was prepared by replacing the trimethylolprapane tripelargonate of Exaabple 1 with an ester formed from trimethylolpropane and a mixture of caprylic acid and 35 capric acid (Emery~ 658). Particularly good properties are exhibited by an ester blend composed of 49 weight percent of trimethylolpropane triisostearate and 510 of the replacement ester.
Ester base stocks having similar ' 40 characteristics may be obtained fram a blend of about 15 to about 55 weight percent trimethylolpropane triisostearate and about 45 to about 85 weight percent sue~~-iTUT~ sH~E-r 2~~~so~
WO 94!05745 , PCT/US93/07570 of the ester formed from trimethylolpropane and the caprylic-capric acid mixture.
A two-cycle engine oil composition was prepared from the specific ester base stocks described herein and the same additive system in the same relative amounts used in Example 1, above. Fuel-oil mixtures containing the specific lubricant composition described herein exhibited good miscibility according to ASTM D-4682.
E~MPLE 3 A solventless, biodegradable base stock was prepared from trimethylolpropane triisostearate (about 75 weight percent) and trimethylolpropane trioleate (about 25 weight percent). The ester base stock thus obtained has the characteristics set forth below in Table IV
TABhE I0 Properties Characteristics Methods Viscosity, cSt ASTM D-45 2 0 loo°c 13.22 40°C 88.89 Viscosity, cp ASTM D-2983 -25°C 26,700 Viscosity Index 149 ASTM D-2270 2 5 Flash Point, °C 293 ASTM D-92 Pour Point, °C -28 ASTM D-97 Biodegradability >90$ CEC L-33-T-82 Ester base stocks exhibiting properties 30 generally similar to those reported in Table IV, above, may be obtained from a blend of about 35 to about 90 weight percent of trimethlolpropane triisostearate and about 10 to about 65 weight percent of trimethylolpropane trioleate.
35 A two-cycle engine oil composition was prepared from the specific ester base stock described herein and the same additive system in the same relative $t,~E~STiT~TE aHEET

05745 ~ PCT/US93/07570 amounts used in Example 1, above. Fuel-oil mixtures containing the specific lubricant composition described herein exhibited good miscibility, remaining according to ASTM D°4682.
E~i~LE 4 .
A solventless, biodegradable ester base stock having desirable biodegradable, flash point and viscosity properties was blended from about 55 weight percent of trimethylolpropane triisostearate and about 45 weight percent of an ester comprising, as its reactive components, trimethylolpropane and a mixture of C5-C9 straight chain saturated monocarboxylic acids (Emery~ 1210 LMW Acid). Ester base stocks having similar biodegradability, flash point and viscosity properties may be obtained from a blend of about 35 to 70 weight percent of trimethylolpropane triisostearate and from about 30 to about 65 weight percent of an ester formed by the reaction of trimethylolpropane and the aforementioned mixture of C5-C9 saturated monocarboxylic acids.
A two-cycle engine oil composition was prepared from the specific ester base stock described herein and the same additive system used in Example 1.
The resultant lubricant composition had a viscosity of less than 10 cSt at 100°C and exhibited satisfactory miscibility with commercial two-cycle engine fuels.

A series of ester base stocks was prepared by blending trimethylolpropane tripelargonate and a complex ester formed by the reaction of trimethylolpropane, a caprylic-capric acid mixture (Emery~ 658) and adipic acid in varying proportions ranging from about 25 to -about 85% of the trimethylolpropane tripelargonate and SUBSTITUTE SHEET

WO 94!05745 PCTIUS93/07570 from 15 to about 75 weight percent of the complex ester, as follows:
Ex. No. 5(a) 5fbl 5(c~ 5(di 5(e~
wt% Complex eater 15.0 26.2 31.0 43.0 52.7 wt% TMP-tripelargonate 85.0 73.8 69.0 57.0 47.3 Certain characteristics of the specif is blends are reported in Table V, which also lists the methods by which the specified characteristics were determined.
Although the various aspects of the present invention have been described and exemplified above in terms of certain preferred embodiments, various c>ther embodiments may be apparent to those skilled in the art.
The invention is, therefore, not limited to the embodiments specifically described and exemplified herein, but is capable of variation and modification without departing from the scope of the appended claims.
SUBSTITUTE SHEET

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Claims (26)

CLAIMS:

1. An ester base stock for a two-cycle engine oil composition, said base stock consisting essentially of a blend of (a) a first polyol ester comprising, as its reactive components, a neopentylpolyol and a C16-C20 branched chain, saturated monocarboxylic acid and (b) a second polyol ester comprising, as its reactive components, a neopentylpolyol and a carboxylic acid selected from the group consisting of at least one C5-C10 straight chain, saturated monocarboxylic acid, and at least one C16-C20 straight or branched chain, unsaturated monocarboxylic acid; and, optionally, a relatively low molecular weight ester comprising, as its reactive components, a C8-C13 straight or branched chain monohydric alcohol and a C5-C12 straight or branched chain carboxylic acid, said ester base stock having the following characteristics:
(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C.

2. An ester base stock as claimed in claim 1, wherein the neopentylpolyol component of said first and said second ester is selected from the group consisting of trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, neopentylglycol, trimethylolethane and mixtures of two or more of said neopentylpolyols.

3. An ester base stock as claimed in claim 2, wherein the acid component of said first ester is isostearic acid, and the acid component of said second ester is selected from (i) the group consisting of caproic acid, caprylic acid, pelargonic acid, capric acid, and mixtures of two or more of said straight chain, saturated monocarboxylic acids, or (ii) the group consisting of palmitoleic acid, oleic acid, and mixtures of said unsaturated monocarboxylic acids.

4. An ester base stock as claimed in claim 1, consisting essentially of from about 10% to about 65%
of said first ester and from about 35% to about 90% of said second ester, based on the weight of said ester base stock.

5. An ester base stock for a two-cycle engine oil composition, consisting essentially of from about 20% to about 60% of trimethylolpropane triisostearate and from about 40% to about 80% of trimethylolpropane tripelargonate, based on the weight of said ester base stock.

6. An ester base stock as claimed in claim 5, consisting essentially of about 42%
trimethylolpropane triisostearate and about 58% of trimethylolpropane tripelargonate, based on the weight of said ester base stock.

7. An ester base stock for a two-cycle engine oil composition, consisting essentially of from about 15% to about 55% of trimethylolpropane triisostearate and from about 45% to about 85% of an ester comprising, as its reactive components, trimethylolpropane and a mixture of caprylic acid and capric acid, based on the weight of said ester base stock.

8. An ester base stock as claimed in claim 7, consisting essentially of about 49%

trimethylolpropane triisostearate and about 51% of an ester comprising, as its reactive components, trimethylolpropane and a mixture of caprylic acid and capric acid, based on the weight of said ester base stock.

9. An ester base stock for a two-cycle engine oil composition, consisting essentially of from about 35% to about 90% of trimethylolpropane triisostearate and from about 10% to about 65% of trimethylolpropane trioleate, based on the weight of said ester base stock.

10. An ester base stock as claimed in claim 9, consisting essentially of about 75%
trimethylolpropane triisostearate and about 25%
trimethylolpropane trioleate, based on the weight of said ester base stock.

11. An ester base stock for a two-cycle engine oil composition, consisting essentially of from about 35% to about 70% of trimethylolpropane triisostearate and from about 30% to about 65% of a mixture of C5-C9 saturated monocarboxylic acids, based on the weight of said ester base stock.

12. An ester base stock as claimed in claim 11, consisting essentially of about 55%
trimethylolpropane triisostearate and about 45% of a mixture of C5-C9 straight chain saturated monocarboxylic acids, based on the weight of said ester base stock.

13. A biodegradable two-cycle engine oil composition comprising:
(A) an ester base stock consisting essentially of a blend of (a) a first polyolester comprising, as its reactive components, a neopentylpolyol and a C16-C20 branched chain saturated monocarboxylic acid and (b) a second polyol ester comprising, as its reactive components, a neopentylpolyol and a carboxylic acid selected from the group consisting of at least one C5-C10 straight chain, saturated monocarboxylic acid and at least one C16-C20 straight or branched chain, unsaturated monocarboxylic acids; and, optionally, a relatively low molecular weight ester comprising, as its reactive components, a C8-C13 straight or branched chain monohydric alcohol and a C5-C12 straight or branched chain carboxylic acid, said ester base stock having the following characteristics:
(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C; and (B) a detergent/dispersant additive, said composition having the following characteristics:
(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C;
(iii) kinematic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/oil ratio of 16:1 to 100:1, of <= 1100 of reference oil, as determined by ASTM-4682, using Citgo-93738 as said reference oil for category 3, according to SAE J1536.

14. A biodegradable two-cycle engine oil composition, as claimed in claim 13, including an ashless detergent/dispersant additive selected from the group consisting of a polyamide, a alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative or a combination of any two or more of said additives.

15. A biodegradable two-cycle engine oil composition, as claimed in claim 13, including an ash-containing detergent/dispersant additive selected from the group consisting of sulfonate phosphonate, an alkaline earth metal, phenate, or a combination of any two or more of said additives.

16. A biodegradable two-cycle engine oil composition as claimed in claim 13, comprising from about 80% to about 90% of said ester base stock and from about 10% to about 20%
of said detergent dispersant additive, based on the weight of said composition.

17. A biodegradable two-cycle engine oil composition, as claimed in claim 14, comprising about 85% of said ester base stock, consisting essentially of a blend of trimethylolpropane triisostearate and trimethylolpropane tripelargonate in a weight ratio of about 0.7:1.0, and about 15% of said additive, said percentages being based on the weight of said composition.

18. A biodegradable two-cycle engine oil composition, as claimed in claim 14, comprising about 85% of said ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and an ester comprising, as its reactive components, trimethylolpropane and a mixture of caprylic acid and capric acid, in a weight ratio of about 1.2 to 1.0, and about 15% of said additive, said percentages being based on the weight of said composition.

19. A biodegradable two-cycle engine oil composition, as claimed in claim 14, comprising about 85% of said ester base stock consisting essentially of trimethylolpropane triisostearate and trimethylolpropane trioleate in a weight ratio of about 3.0:1.0, and about 15% of said additive, said percentages being based on the weight of said composition.

20. A biodegradable two-cycle engine oil composition, as claimed in claim 14, comprising about 85% of said ester base stock consisting essentially of trimethylolpropane triisostearate and a mixture of C5-C9 straight chain saturated monocarboxylic acids, in a weight ratio of about 1.2:1.0, and about 15% of said additive, said percentages being based on the weight of said composition.

21. A method of lubricating a two-cycle engine which comprises bringing the components of said engine which are to be lubricated into contact with an effective amount of the composition of claim 13.

22. A method as claimed in claim 21, wherein said engine is lubricated with a composition comprising about 85%
of said ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and trimethylolpropane tripelargonate, in a weight ratio of about 0.7:1.0, and about 15% of an ashless detergent/dispersant additive selected from the group consisting of a polyamide, an alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative, or a combination of any two or more of said additives, said percentages being based on the weight of said composition.

23. A biodegradable two-cycle engine oil composition comprising:
(A) about 85% of an ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and trimethylolpropane tripelargonate in a weight ratio of about 0.7:1.0, said ester base stock having the following characteristics:
(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C; and (B) about 15% of an additive selected from the group consisting of a polyamide, a alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative and a combination of said additives, said percentages being based on the weight of said composition, said composition having the following characteristics:
(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C;
(iii) kinematic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/oil ratio of 16:1 to 100:1, of <= 1100 of reference oil, as determined by ASTM-4682, using Citgo-93738 as said reference oil for category 3, according to SAE J1536.

24. A biodegradable two-cycle engine oil composition comprising:
(A) about 85% of an ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and an ester comprising, as its reactive components, trimethylolpropane and a mixture of caprylic acid and capric acid, in a weight ratio of about 1.2 to 1.0, said ester base stock having the following characteristics:
(i) biodegradability of >= 800, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C; and (B) about 15% of an additive selected from the group consisting of a polyamide, a alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative and a combination of said additives, said percentages being based on the weight of said composition, said composition having the following characteristics:
(i) biodegradability of >= 800, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C;
(iii) kinematic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/oil ratio of 16:1 to 100:1, of <= 110% of reference oil, as determined by ASTM-4682, using Citgo-93738 as said reference oil for category 3, according to SAE J1536.

25. A biodegradable two-cycle engine oil composition comprising:

(A) about 85% of an ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and trimethylolpropane trioleate in a weight ratio of about 3.0:1.0, said ester base stock having the following characteristics:

(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of 175°C; and (iii) kinematic viscosity of less than 15 cSt at 100°C; and (B) about 150 of an additive selected from the group consisting of a polyamide, a alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative and a combination of said additives, said percentages being based on the weight of sad composition, said composition having the following characteristics:

(i) biodegradability of >= 80%, as determined by CEC-L-33-T-82;
(ii) flash point of >= 175°C;
(iii) kinematic viscosity of less than 15 cSt at 100°C; and (iv) miscibility with gasoline, in a fuel/oil ratio of 16:1 to 100:1, of >= 110% of reference oil, as determined by ASTM-4682, using Citgo-93738 as said reference oil for category 3, according to SAE J1536.

26. A method of lubricating a two-cycle engine which comprises bringing the components of said engine which are to be lubricated into contact with an effective amount of a composition comprising about 85% of an ester base stock consisting essentially of a blend of trimethylolpropane triisostearate and trimethylolpropane tripelargonate, in a weight ratio of about 0.7:1.0, and about 15% of an ashless additive selected from the group consisting of a polyamide, an alkenylsuccinimide, a boric acid-modified alkenylsuccinimide, a phenolic amine, a succinate derivative, and a combination of said additives, said percentages being based on the weight of said composition.